1. Field
Example embodiments of the following description relate to a method and apparatus for estimating a three-dimensional (3D) position and orientation based on a sensor fusion process, and more particularly, to a method and apparatus for estimating a 3D position and orientation by fusing a result of position estimation, based on a marker and a result of position and orientation estimation based on inertial information.
2. Description of the Related Art
Conventionally, techniques that estimate a three-dimensional (3D) position and orientation of a moving object or target have been used in film, graphic and animation industries, and the like for sensing a motion of an object, a human body, an animal, and the like in a 3D space using an expensive and large-sized motion capture device.
As a motion sensing technique for consumer electronics (CE) associated with the game industry has begun to draw attention, many 3D position and orientation estimating methods using an inexpensive and small-sized motion capturing device have been developed.
A 3D position estimating method in a space is classified into a few methods, namely a method based on a camera, a method based on an infrared light, a method based on an inertial sensor, and the like.
According to the method based on the camera, locations of markers or light sources formed in images obtained from a plurality of two-dimensional (2D) cameras are transformed into a 3D position in a space. In this case, performance is dependent on the resolution of the cameras, sizes of the markers, and the like, and thus, the method may be problematic when performing high precision sensing.
According to a method based on an ultrasonic wave, a distance is calculated by measuring a time of flight (TOF) corresponding to a time taken for an ultrasonic wave to travel from a transmitting unit to a receiving unit and using the fact that ultrasonic waves propagate at the speed of sound, that is, about 340 meters per second (m/s). The 3D position is calculated based on a triangulation process, for example, after obtaining at least three pieces of distance information obtained at the same point of view. The method based on the ultrasonic wave may perform a high precision sensing using a device that is relatively less expensive than devices with a high cost, such as cameras. However, simultaneous transmission of ultrasonic waves is difficult to realize due to inter-sound wave interference, which presents a difficulty in estimating a position with respect to a moving object in real time. The problem is due to an attenuation time of an ultrasonic wave signal, that is, about 100 milliseconds (ms) taken over a distance of 3 meters (m).
According to the method based on the inertial sensor, the 3D position is calculated by applying integration to an acceleration component computed, based on an acceleration and a gravity acceleration, obtained through an accelerometer sensor and a gyro-sensor, and an angular velocity. However, the method based on the inertia is able to perform position estimating within a short time period and is not appropriate for long-time position estimating, since errors are accumulated over time.